I'm going to go BBK (front&rear) on my 2016 honda accord coupe - it's not a branded kit, I will use fastbrakes adapters for both axles. Basically the kits use 350z rotors at the front and pilot rotors at the back, Advic calipers for the front and integra ones for the rear.
Yes, I admit that the look is important to me, but does not prevail over the function. Some people try to scare me off from doing this mod giving arguments that sound resonable: The car is new, highly engineered, it's more probable to spoil the set-up than to improve anything, it will impair the ABS and traction control function, etc.
I'm not an expert so my question is if it's possible to do this mod safely and keep the car's braking balance. If it is, what should I do except for careful bleeding?

 

I'd say there's about a 0% chance you maintain the OE balance. Now, whether it creates a problem or not is a different story. You'll have to see how things behave. I would ease into it; don't go out and try a 100 to 0 stop your first go at it. In the end, you only stop as well as your tires allow.